The elusive art of jazz has proven notoriously difficult to capture on film, as has been amply demonstrated by films such as Clint Eastwood's ponderous Charlie Parker biography "Bird" (1988) and Ken Burns' stultifying, multi-part documentary "Jazz" (2001).

But a few efforts have proven that it's possible to do justice to the quintessentially American art form, among them Bertrand Tavernier's bittersweet feature "'Round Midnight" (1986), Bert Stern's visually and musically sumptuous documentary "Jazz on a Summer's Day" (1959) and the animated, Oscar-nominated "Chico & Rita" (2010).

In its own idiosyncratic way, Dwayne Johnson-Cochran's new documentary "Be Known" – which has its first, sneak-preview screenings starting Friday at the Gene Siskel Film Center – belongs to the small category of films that not only respect the art of jazz but illuminate it.

Not that "Be Known," which carries the subtitle "The Mystery of Kahil El'Zabar," glamorizes the music or El'Zabar, a brilliant but enigmatic Chicago jazz innovator. On the contrary, the film shows El'Zabar in decidedly unflattering scenes, yet also in moments of viscerally exciting performance. Better still, "Be Known" gives listeners an unflinching, eyes-wide-open look at a jazz musician's daily life, with all the triumphs and humiliations that entails.

What's most startling here is the candor of the film and of El'Zabar, who surely reveals more of himself, his music and his travails than most individuals would dare. Yet he didn't really intend to do so, at least at the outset.

"He kind of wanted me to think about making the film in the PBS way," says director Johnson-Cochran, who grew up with El'Zabar on the South Side of Chicago and has been fascinated by him since their youth. "You know, sit down, (film) people who praise him, all the work he's done over the years.

"That would be pretty sterile for this, man. He is an innovator. And in innovation comes messiness, and some very, very prominent people in the world are extremely talented in making things, but they have a messy, messy, messy life. And Kahil has that life."

El'Zabar's troubles emerge early in the film, which centers on a six-week road trip across America in 2006 but also features footage shot in its aftermath. We soon learn that El'Zabar is being pursued for back child support, and his woes deepen as the film progresses. As his students are presenting a performance, we learn that police marshals have shown up with a warrant for his arrest, the disastrous news covered in the Tribune and readily seen on the Internet.

But that's only part of the complexity of El'Zabar's life. For all the critical accolades and awards that El'Zabar has garnered around the world, he observes the financial challenges of his life. He doesn't own a piece of property or a car and has fathered seven children by different women. Chaos seems to be the driving factor of his personal life, and he acknowledges the difficulties he faces.

How was Johnson-Cochran able to coax so many hard truths from an artist widely considered one of the most accomplished percussionist-bandleader-composers in avant-garde jazz?

Because of "the years we've known each other," says Johnson-Cochran. "There were times when the camera to him wasn't there. He was talking to me. … It's a very rare (for) a filmmaker to have the level of intimacy we have. He forgot the camera was on – he was talking to my eyes, as opposed to a camera with the red light on.

"He probably said some things that he wished he hadn't said to me. But it's so completely raw that he probably would never take it back, because that's who he is."

Still, Johnson-Cochran braced himself for the worst when he first showed El'Zabar the footage he had accrued during several years of filming.

"He didn't like it," recalls Johnson-Cochran. "He had an idea about how he wanted to be portrayed. … It was painful for him. I know it was. … It didn't sit well for awhile, I could tell. But then he embraced it."

El'Zabar concurs.

"When I saw the rough cut, I was like, 'Woah,'" says the musician. "But people that know me would say if there's a guy who could handle being that naked, I'm probably the guy that could. …

"It's a life, a life of purpose, and anything that has real purpose is not regular. … A lot of times people feel that the picture that should be painted would be perfect, but that's not really life.

"I wouldn't say that all of the things that I've done I'm proud of. But I'm proud of the choices I've made as a musician and as a man and as a human being, and I'm willing to live with the results of the circumstances that I've chosen. But I think and I believe in the end what will stand out is the quality of the work I've produced."

Surely the depth of El'Zabar's musicianship, the virtuosity of his technique and the creativity of his approach as improviser, composer and bandleader are beyond dispute and energize the film. The sheer ferocity of El'Zabar's performance as percussionist and vocalist have no equals in jazz today; he's a singular figure.

All of that explosive intensity, however, has a tendency to singe those around him, as the film reveals. In various performance sequences, El'Zabar storms off the stage, berates his colleagues and otherwise damages musical relationships he needs. Offstage and on the road, anarchy often reigns, El'Zabar juggling phone calls from his children, encounters with the opposite sex and escalating difficulties over child support. He turns up late for performances and classes, engendering resentment from various parties.

But El'Zabar, too, suffers bruises as he pursues his art. Clubs are sometimes nearly empty. Posters promoting his shows often misspell his name, the presenters oblivious of who he is. Before one show, he's forced to change clothes in a cramped storage room. Respect is not widely given.

For those who think the jazz life radiates a certain glamour, "Be Known" argues poignantly otherwise.

It's all up there on the screen, as is the kind of locker-room chatter that will not win El'Zabar any fans among feminists.

"If you're around ball players, rockers, rock stars or violinists or around reporters, (they) talk about women in a certain way," says Johnson-Cochran. "I just caught it on tape."

So did Johnson-Cochran ever unravel the mystery of El'Zabar? Did he come to understand why his friend counterbalances high musical achievement with seemingly self-destructive acts, onstage eloquence with offstage disasters?

Having all those children "does shackle him financially, then he gets arrested," says Johnson-Cochran. "OK, why would you have this need to do this? I haven't quite understood why he feels he needs to have that drama….

"He's a very complicated man. … And one thing I think about Kahil is that he does what he wants. Once people see him for all his generosity that he has – but you cannot separate the other half of him, which can be difficult.

"And if you can take the good with the bad and you walk out of the film, you'll see somebody very, very special.

"He's a great partner, a great collaborator, a great friend, but he's a rogue. And that's the cool thing about him. There aren't a lot of real rogues in the world.

"He is a pure-to-the-core rogue, or a rake. And he's not a phony. No way."

Indeed, love him or loathe him or both, El'Zabar remains a force of nature, impossible to harness and stunning to behold.

Which perhaps helps explain the galvanic power of his art.

To read more from Howard Reich on jazz, go to chicagotribune.com/reich.